Power lawn mowers typically incorporate a system for adjusting the height of cut of the lawn mower blade. For example, a typical rotary power mower that includes a rotary mower frame or deck, wheels supporting the deck, a handlebar assembly, a cutting blade, and an engine for rotating the blade wherein the motor is mounted on the deck, usually includes a system for adjusting the height of the cutting blade in relation to the ground over which the rotary mower sits or traverses. A typical height of cut adjustment system incorporates height adjustment mechanisms that are located between the rotary mower deck and the mower wheel assemblies. These height adjustment mechanisms typically are configured so that the operator can choose one of several height settings that best suits the mowing conditions. The mechanisms usually include a lever that is movable fore and aft to various detented positions wherein the detented positions represent various height settings for the mower blade. Actually, the mechanisms and their detented levers, which are interposed between the wheels and the mower deck, are configured so that movement of the detented levers raises or lowers the entire mower deck relative to the ground engaging wheels. Since the engine is mounted directly on the deck, the engine moves up and down with the deck as the deck's height is adjusted relative to the wheels by the height adjustment mechanisms. The blade, which is rotatably mounted on the engine, then moves up and down with the engine and the deck as the deck's height is adjusted relative to the wheels by the height adjustment mechanisms.
It is highly desirable to have the capability to adjust the blade up or down relative to the ground and grass to be cut. If one wants to cut the grass so that the grass blades are cut short, then the height adjustment mechanism levers are moved to a detented position where the deck, engine and blade are lowered to a position closer to the ground and grass. If the grass to be cut is quite thick or long, then it will be desirable to set the deck, engine and blade higher so that a smaller portion of the grass is cut off. If one tries to cut too much grass at once, the mower deck can clog with grass clippings and/or the mower engine can bog down or stall. This is especially true in mulching type mowers that cut and recut grass clippings without discharging the clippings through a side or rear discharge chute.
Determining how much grass to cut and at what height the blade should be set at is generally a subjective process. That is, the operator will typically survey the grass to be mowed and will then set the blade at a height that the operator deems proper. If the mowing performance is not adequate, the operator might have to change the height setting again to achieve an adequate cut. For example, if the mower encounters grass that is too thick or too long, the engine might begin to labor or bog down, or the grass clippings might begin to clump together and leave the freshly mowed area in a less than attractive condition. Again, mulching mowers are more prone to this condition, and proper blade height setting is critical to achieving an attractive grade of cut with a mulcher. To remedy this condition, the operator would need to raise the blade height so that smaller clippings are generated, thus reducing the volume of clipping mass underneath the mower deck.
If the blade had originally been set too low and, as a result, had scalped the lawn and ground in several places, then again the operator would have to stop the mowing process and raise the cutting blade to stop the scalping condition. Conversely, if the operator had originally set the blade too high and, while mowing, had determined that not enough grass was being cut, then the operator would have to lower the cutting blade so that a greater portion of the grass blade is removed.
Unfortunately, the operator typically has to guess at which height the blade should initially be set by surveying the grass conditions and then choosing a blade height setting that, in the operator's opinion, will do the best job of cutting the grass to a desirable level. When using a mulching mower, the operator's task is more difficult since the proper height of cut is critical to achieving an attractive grade of cut that is free of clumps of grass clippings.
One prior art lawn mower height of cut adjustment system is disclosed in U.S. Pat. No. 3,972,160 issued to Boswell on Aug. 3, 1976. In Boswell, the lawn mower 1 includes a body (frame) 2 which is supported by rear wheels 3 and front wheels (not numbered or shown). A height adjustment mechanism H is interposed between one of the rear wheels 3 and the body 2. The height adjuster mechanism H includes an adjusting lever 13 and a mating, numbered, detented slot member 19. The operator can move the lever 13 fore and aft within the slot member 19 to raise or lower the mower body 2. Since the engine and the blade are mounted directly on the body 2, the blade moves up or down with the body 2 when the body 2 is raised or lowered by the lever 13. In Boswell, a single height adjuster mechanism serves to raise or lower the body 2 through a series of interconnected rods and plates that pivot all four mower wheel assemblies so as to raise or lower the entire mower body. Boswell does not disclose any gauge for measuring the height of the grass blades to be cut. In fact, Boswell, in column 3, lines 16 through 22, discusses the need for the operator to adjust and readjust the height setting as the operator determines necessary.
Another prior art lawn mower height of cut adjustment system is disclosed in U.S. Pat. No. 3,114,229 issued to Wilson on Dec. 17, 1963. In Wilson, the lawn mower includes a deck 1 on a rotary lawn mower. The deck 1 has a motor 4 mounted on it. Wheels support the deck 1 and a handlebar 7 is connected to the deck 1, providing means for the operator to propel and control the mower. A blade height adjustment mechanism in the form of a cylindrical tube 20 is mounted on and extends vertically from the deck 1. The height adjustment tube 20 includes an adjustment knob 44. A set screw 52 which is threaded into the side wall of the cylindrical tube 20 engages the blade shaft assembly 5 which is journalled in and rotates within the tube 20. A cutting blade is attached to the lower end of the shaft 5 wherein the lower end of the shaft is underneath the deck 1. By rotating the set screw 52 counterclockwise, the shaft 5 is free to move up and down within the tube 20 and can be so moved by rotating the blade height adjustment knob 44. Since the blade is attached to the shaft 5, movement up or down of the shaft 5 moves the blade up or down relative to the deck 1 and the grass to be cut. The tube 20 also includes a set of markings 53 that are located adjacent to a blade height indicator 50 which moves up or down with the shaft 5 and blade. Once the operator has chosen a desired height setting by rotating the adjustment knob 44 and by referencing the blade height markings 53 on the tube 20 and the position of the indicator 50, the operator rotates the set screw 52 to restrain the shaft 5 from further up or down movement within the tube 20. Wilson does not disclose any gauge for measuring the height of the grass blades to be cut. The operator must estimate the height of the grass and guess at which blade height setting is most appropriate for the lawn to be mowed.
Another prior art lawn mower height of cut adjustment system is disclosed in U.S. Pat. No. 2,961,251 issued to Roberton on Nov. 22, 1960. Roberton discloses a lawn mower with a housing 10 supported by four wheels A handlebar assembly 15 is coupled to the deck 10. An internal combustion engine 12 is mounted on the deck 10 and rotatably drives a cutting blade (not shown). Wheel height adjustment assemblies are located between the deck 10 and the wheels 11. Blade and deck height adjustment is accomplished by pulling the wheel discs 43 out away from the wheel hubs and by then rotating the wheel discs in increments of 90 degrees to another detented position. The wheel discs 43 are marked in 90 degree increments with numerals indicating the actual height of the blade off of the ground wherein the numeral on the wheel disc 43 that is in the twelve o'clock high position is the current blade height. Roberton does not disclose any gauge for measuring the height of the grass blade to be cut. The operator must estimate the height of the grass to be cut and guess which blade height setting is most appropriate for a satisfactory cut.
Another prior art lawn height of cut adjustment system is disclosed in the "TORO 21" Recycler Mower Operator's Manual, form number 3324-706, copyright 1991. The "TORO" Operator's Manual discloses, on page 6, a lawn mower height of cut adjustment system that incorporates a wheel height adjuster mechanism that is interposed between the mower wheels and the mower deck. The wheel height adjuster includes a lever that is movable fore and aft. The fore or aft movement of the lever raises or lowers the deck, engine, and cutting blade. The wheel height adjuster also includes a set of notches in the deck for receiving and restraining the lever once a blade height is selected. Reference letters are located adjacent to the notches indicating the particular height setting of each wheel. The reference numerals enable the operator to compare the height settings of each particular wheel so that each wheel is set at the same height. The "TORO" Operator's Manual does not disclose a gauge for measuring the height of the grass to be cut. The operator must survey the grass to be cut and then estimate what the proper height setting should be to achieve a satisfactory cut. FIG. 7 on page 6 of the manual does provide a table showing the actual blade heights that correspond to each wheel height setting represented by a reference letter.
The present invention offers an alternate lawn mower height of cut adjustment system. In particular, a preferred lawn mower height of cut adjustment system according to the present invention incorporates a mower frame, a cutting blade rotatably supported by the frame, a ground engaging wheel coupled to and supporting the frame, means for adjusting the height setting of the blade relative to the ground engaging wheel, and a grass height gauge operatively connected to the frame wherein the grass height gauge indicates a desirable height setting for the cutting blade so that a predetermined portion of the standing grass blade is removed.